In this post, we will answer if shrimp are fish. We will also outline the shrimp biology and needs in a tank.
Are shrimp fish?
No, shrimp are not fish, they are crustaceans. Crustaceans form a group of animals that belong to the Arthropoda phylum and, therefore, present typical characteristics of this phylum. The Arthropoda characteristics are the presence of an exoskeleton, articulated legs, and segmented body. The subphylum Crustacea has this name because of the presence of an exoskeleton impregnated with calcium carbonate. This exoskeleton guarantees greater protection when compared to other arthropods exoskeletons.
Crustaceans have more than 60,00 species. As representatives, we can mention crabs, shrimp, crayfish, and lobsters. These groups are mostly found in the aquatic environment, but there are also terrestrial species.
Crustaceans have an enormous morphological variety, it is considered one of the most diversified groups. The smallest crustacean is around 100 µm, and the largest have up to 4 metres of the leg opening, such as the Japanese spider crab.
General characteristics
Crustaceans have bilateral symmetry and a body divided into cephalothorax and abdomen, or sometimes head, thorax and abdomen. As stated, their exoskeleton is formed by chitin and calcium carbonate, which increases this structure strength. They have two pairs of antennas on their heads. The other arthropods groups usually have only one pair. They also have a pair of upper jaws and a pair of lower jaws.
Gas exchanges normally occur through the gills or specialized cavities on the surface of their body. Oxygen is transported through the blood (hemolymph) in solution or associated with haemoglobin or hemocyanin.
Their nervous system is composed of the brain, nerve cords and ganglia. They have ocelli or multifaceted eyes. The ocelli are often over mobile peduncles in most adult individuals. The digestive tract of these animals is complete and excretion occurs through the maxillary or antennal glands, blind sacs that open in the jaws or antennae, respectively.
Crustaceans are generally dioecious, which means they have separate sexes However, there are also hermaphrodite species, such as barnacles. Fertilization is internal – usually with copulation – and development is usually indirect (with a larval stage). However, there are species with direct development (without larval stage).
Economic and ecological importance
Crustaceans occupy different trophic levels, being especially important in aquatic food chains. There is a wide variety of diets and ways of feeding, as predatory, filter feeders and even parasites. It is important to mention the presence of microcrustaceans in the composition of zooplankton – the group of primary consumers in various aquatic environments. It is worth noting that crustaceans are known mainly for their economic importance, since they are widely used for human consumption, such as shrimp and lobster.
Shrimp and their characteristics
The name shrimp is traditionally given to a group of aquatic crustaceans, mainly marine but can be also freshwater, formerly grouped in the suborder of swimming decapods.
They feature a thin and flexible exoskeleton and a cylindrical body. In general, shrimp are scavengers, feeding on organic debris that is dispersed in the substrate. There are also shrimp that remove parasites from the skin of fish for food.
Anatomy
The body of shrimp is covered by a carapace impregnated with calcium salts and is divided into three regions: the cephalothorax, in the anterior part; the abdomen, where the 5 pairs of locomotor appendages or legs are inserted; and the telso, on the back. Shrimp have long and thin antennae, as well as a set of mouth appendages used for feeding. They swim forward but, if frightened, they can quickly move backwards.
Shrimp distribution
The shrimp distribution area comprises the Atlantic Ocean, the Mediterranean Sea, regions of the Pacific Ocean, continental shelves, muddy streams, rivers and lakes. They can also inhabit wetlands. Some species are very important in the oceanic food chain, as they are the basis of nutrition for large marine mammals — i.e. sperm whales — and for several fish.
Some shrimp species can reach about twenty centimetres in length, but most species are smaller, and sometimes even microscopic. Freshwater shrimps are called prawns.
Shrimp reproduction
Shrimp are unisexual (male or female). However, some males can change into females after a certain time, which on average takes about two years. In addition, female shrimp can mate after moulting (shell change). Taking into account these conditions, the female can only mate three times a year, usually during the spring, summer and mid-winter.
The number of eggs laid by females increases with their age. Thus, at the age of three years, a female shrimp can lay more than 25,000 eggs. Once fertilized, the eggs are kept on the female’s abdomen with a sticky mucus secreted, which protects the future offspring from predators. The female keeps the eggs until they hatch. The hatching period varies according to the temperature of the water. Therefore, during the summer, the process can take up to four weeks, while during the winter it can take up to three months.
It is possible to determine the status of egg maturation by its colour. If most of the eggs are dark, it is very close to hatching. After the eggs hatch, the young shrimp remain swimming on the water column. They will only go close to the substrate lately.
Is it possible to raise shrimp in a tank?
Aquarium shrimp come in many diverse colours, shapes and sizes. They help in cleaning and balancing the tank water and structures. Another interesting fact is that there are very low-maintenance species, which can be raised by beginners.
Shrimp have a very interesting function in the aquarium. They are part of what we call the cleaning team, as are the snails.
Cleaning shrimps
The cleaning team has a very beneficial impact on your aquarium, as they are detritivore animals. They help to eliminate those residues that pollute your tank, such as leftovers, decomposing pieces of dead fish or even plants. Once shrimp are small animals and move throughout the aquarium easily, they can reach places that we do not have easy access to, or that we just cannot see. Avoiding accumulation of pollutants and waste in the tank.
Fish and shrimp in the same tank
It is possible to keep fish and shrimp together, but it is always good to remember that if a shrimp fits in the fish mouth, it will likely be eaten. So it is better to have shrimp with small, peaceful fish.
Still, the hatchlings are so small that any fish could eat them. Thus, if you plan to breed shrimp in your tank, you should consider keeping only the shrimp. Planted aquariums help you with this because it allows the young to hide among the plants.
Shrimp parameters for the tank
Ideal needs and parameters change according to the species of shrimp, but there are some very important points. They are often much less tolerant to ammonia than fish. In addition, you will need to keep all the other recommendations for maintaining your tank water quality, like having a good filter and not overpopulating the tank.
Another very important point is that they are extremely sensitive to metals in water. Some medicines and fertilizers can have a very high concentration of copper or iron, which can seriously harm any crustacean, especially shrimp. The damage can range from stopping reproduction to death and, thus, the end of your shrimp colony.
Conclusion
In this post, we determined if shrimp are fish. We also outlined their basic biology and needs in a tank.
If you have any thoughts or doubts, feel free to drop us in a comment below!
Frequently Asked Questions (FAQs): Are shrimp fish?
What is the economic importance of shrimp?
Shrimp are part of the diet of thousands of people around the world. In the United States, each American eats, on average, 1.8 kilograms of shrimp in a year. The problem is that as tasty as this crustacean is, the industrialization process of shrimp has devastating ecological consequences.
What is shrimp food?
The main item in a shrimp diet is seaweed. These crustaceans are able to find the source of energy, carbohydrates, and fibre they need to survive from plants. If you do not want to offer another type of food in your tank, algae are enough to meet their physiological needs.
What are the shrimp development stages?
The development of almost all shrimp is composed of three phases: nauplii, zoea, and post-larvae. In shrimp, the nauplii stage takes place inside the egg, and the hatchlings are born as zoea.
What is the name of the giant shrimp?
Giant tiger prawn belongs to the species Penaeus monodon and can be found in the Indus Pacific.
How many centimetres is the largest freshwater shrimp?
The largest shrimp in the world is the crustacean known as Pitu, this prawn lives in the Amazon river basin (Brazil). Its scientific name is Macrobrachium carcinus, the record holder measured 48 centimetres in length, from the tail to the tip of the claws, and weighted more than 300 grams.
References
De Grave, S., Cai, Y., & Anker, A. (2007). Global diversity of shrimps (Crustacea: Decapoda: Caridea) in freshwater. In Freshwater Animal Diversity Assessment (pp. 287-293). Springer, Dordrecht.
Shrimp Reproduction. http://shrimpreproduction.weebly.com/major-stages-in-the-life-cycle.html/
Mukai, H., & Koike, I. (1984). Behavior and respiration of the burrowing shrimps Upogebia major (de Haan) and Callianassa japonica (de Haan). Journal of Crustacean Biology, 4(2), 191-200.
